This invention relates to box or case sealers, being apparatus to seal the ends of cardboard boxes or cartons and the like. In particular, the invention relates to semiautomatic case sealers, where the box flaps are already folded closed and it is just desired to seal them shut.
In the packaging industry, many products are packed in cardboard boxes or cartons for shipping. Often, one end of the box, namely the bottom, is sealed shut before the box is filled, and after the box is filled, the top end of the box has to be sealed shut. The top end of the box is usually comprised of end and side flaps that are folded inwardly and downwardly. The box can be sealed by applying glue to the inside or mating surfaces of the folded flaps prior to them being folded, or by applying some other fastening device to the outside of the flaps after they have been folded shut.
In most cases, the boxes are uniform in size, so providing apparatus that will apply some sealing device to the flaps, and perhaps even fold them into a closed position, is not particularly difficult to do. The apparatus can be adjusted to suit the known width and height of the boxes and there is no problem running the boxes through the case sealer once it is adjusted properly.
However, sometimes the boxes are used to pack articles that are not uniform in size, with the result that the boxes are overfilled or underfilled. In some instances, it is also desirable to be able to handle boxes of different sizes coming down the same conveyor line. In these instances, a random case sealer is required, wherein the apparatus for applying the sealing device to the box flaps adjusts automatically to suit the size of the box.
In prior art random case sealers, various sensors have been used to determine the exact size and position of the boxes in the case sealer, and numerous actuators or other adjusting mechanisms, together with programmable logic controls have been used to adjust the position of the various folding and sealing components in response to what is sensed by the sensors. A difficulty with this type of apparatus is that the numerous sensors and actuators are prone to mechanical breakdown and expensive maintenance problems. Further, an overfilled box is not uniform in shape, so the sensors often cannot determine the optimum position adjustments, with the result that the boxes get jammed in the apparatus shutting down the packaging line.